Method of making insulated linings for tanks



Sept. 17, 1957 s. BECKWITH 2,306,810

METHOD OF MAKING INSULATED LININGS FOR TANKS Filed Oct. 8, 1954 2 Sheets-Sheet 1 m m Illlllll W iii' .umligin'n'; 11.

Lu INVENTORL l Sterling Beckwith 1 Parker 8: Curt er ATTORNEYS Tlllllllllllllll u S. BECKWITH Sept. 17, 1957 METHOD OF MAKING INSULATED LININGS FOR TANKS Fild 001;. 8, 1954 2 Sheets-Sheet 2 I Jr Ill llll lllllll llllll I INVENTOR,

Sterling Beckwiih v By Parker 8: Carter ATTORNEYS 2,806,810 Patented Sept. 17, 1957 lWE'IHGD OF MAKING INSULATED LININGS F912 TANKS Sterling Beckwith, Lake Forest, 111., assignor, by mesne assignments, to Constcck Liquid Mlethane Corporation, a corporation of Delaware Application October 8, 1954, Serial No. 4615953 8 Ciaims. (Cl. 154-82) My invention involves the method of effectively manufacturing and preparing a multiplicity of relatively thin insulating panels which may be assembled inside a tank a ainst the inner periphery of the wall thereof and make it possible to insulate such cold liquids as methane and the like which boil at temperatures far below zero degrees R, while preventing contact of the liquid with the metal tank wall.

Since such insulating lining is supported only on its outer periphery by the metal tank wall and is intended to be in direct contact on its inner periphery with the cold liquid, it is essential that some type of lining material be used which is strong enough to be self-supporting as a tank lining and is not deleteriously affected by the cold liquid.

1 have found that balsa wood is such a material though other materials can be used but balsa wood is light, is an effective insulator, is strong enough to support itself even at the very low temperatures, such as -2S8 F. involved and does not deteriorate as a result of the low temperature or the contact with the liquid.

It is desirable to store such a liquid in vertically disposed cylindrical tanks having generally flat roofs and floors and such tanks may well be in the order of fifty feet or more in diameter and twenty feet or more in height. ing lining will usually come to the tank manufacturer in a multiplicity of small sections usually generally rectangular and a few inches on the side and several feet long. I propose to build up from these pieces a multiplicity of flexible panels which may be bent, without danger of unduly stressing the material, to conform to the peripheral contour of the cylindrical walls. This requires a relatively thin panel from an inch to maybe an inch and a half in thickness and these panels will subsequently be assem bled in the tank, cemented in place and cemented together and pre-stressed so that when the panels shrink as a result of the impact of the cold liquid on them, they will not crack or be pulled apart and will interpose between the liquid and the wall of the tank a continuous insulating lining which will prevent contact of the liquid with the metal tank walls.

In order that these panels may be used to assemble a laminated tank lining they must be of such size that they can be placed in the tank and handled and assembled in the tank so that the panels may be cemented together, and glued in place in the tank for the building up of a suitable continuous laminar pro-stressed balsa wood linmg.

For example, though the dimensions are not controlling, I propose to build up a multiplicity of such relatively thin flexible panels or lining segments approximately an inch and a half thick, nineteen or twenty feet long and approximately four feet wide.

The first step in the process takes the form of squaring the sides and ends of the random dimensioned balsa pieces. The ends must be perpendicular to the axis of the pieces and the sides must be perpendicular to one Balsa wood or other usable adequate insulatanother and to the ends. The pieces in cross section may be square or rectangular and so dimensioned that when laid on a work bench side by side with the long axis of the pieces parallel with the axis of the strip being formed, the thickness of the strip will be generally uniform. The width of the various pieces may be different so long as all the sections in line are of the same width.

Each of such pieces may be then morticed adjacent both ends, a cross out being made to provide interlocking wedging hooks so that all of the pieces in one line may be hooked together to give an interlock during assembly of the strip. The interlocks are tapered so that when pressed together a tight joint will be made independent of any glue or cement placed on the surfaces of the joint. The strip is built up of a multiplicity of these separate interlocking pieces arranged side by side with the interlock perpendicular to the plane of the strip. The interlocking surfaces will be coated with a thin film of glue or cement and the opposed sides of the sticks or pieces will also be coated with cement.

As the strip or ribbon is built up of a plurality of these sticks or pieces arranged and physically interlocked end to end, the strip will be drawn through a glue setting zone Where limited pressure will be first applied to the face of the continuous strip of assembled wood sticks. ressure will then be applied to the two sides of the ribbon to squeeze the glued edges of the pieces together, then additional pressure will be applied to the face of the ribbon and then the glue will be dried or set by dielectric heating. As a matter of convenience the gluing area in which pressure is applied to the forming ribbon of wood both perpendicular to the face and against the edges of the wood might be approximately six feet long by four feet wide. The assembly and gluing of the additional separate sticks of wood will continue after the panel has moved forward six feet to the drying and compression zone and as soon as drying is completed the panel will be moved forward another six feetj When the ribbon, the sticks forming it preferably interlocked mechanically end to end and also glued at the interlocking surfaces and at the surfaces between separate sticks is built up to a length of approximately twenty feet, a thick panel will be cut off to that length.

For convenience in assembly such panel is thicker than the panel which will ultimately be installed in the tank. The thick panel is fed forwardly against a saw which splits it so that there results two flexible panel members, each of substantially half the thickness of the ribbon. These panel members are then separated and dried, preferably in a dry room which will reduce the size of the panel by something like one to two percent of the size under normal moisture content conditions. The shrinkage of the panel must be not less than and preferably slightly greater than the shrinkage of the panel which would result from lowering its temperature from room temperature down to 258 F.

it is this shrinkage which provides at least part of the pre-cornpression of the panel after it is assembled in the tank because if the low moisture content is maintained until the lining is assembled in the tank and if then moisture is allowed to expand the panel to normal moisture content, the panel will be pre-compressed as a result. Such pre-cornpression should usually be at least somewhat greater than the shrinkage which will also result when the cold gas or cold liquid cools the panel down to the low temperature.

After such panels have been dried, they must then again be squared up so that the ends are perpendicular to the axis of the panel and the opposed faces are smooth, perpendicular to one another and perpendicular to the ends of the panel. This provides panels or segments of accurately controlled size and shape. Successive panels low humidity is maintained to prevent substantial excessive moisture pick up until after the panels have been arranged in the tank, glued'in place under pressure.

Balsa wood is a light, relatively soft material. Since all six surfaces of each panel segment are to be cemented or glued to opposed panels, distortion or mutilation of the surface would be highly undesirable. Therefore, means for handling or moving the panels would present serious problems.

What I propose in this connection is to provide a vacuum pad which may be placed on the ribbon as it projects beyond the gluing station. This vacuum pad will grip the face of the panel Without distorting it and as step by step the ribbon is fed out, the vacuum will be released and the pad lifted up and moved back near the gluing station so that step by step the ribbon is drawn forwardly.

When a panel segment has been cut ofi from the ribbon the vacuum pad will be placed in contact with the unsevered portion of the ribbon. Movement'of the ribbon engaging the end of the just cut off section willforce the ribbon forwardly through the slitting area.

The mortised joints between the abutting ends of the pieces assembled to form the ribbon are largely a matter of convenience as they hold the aligned strips together before the glue is set and make it possible to draw the ribbon through the glue setting area. If desired, however, the sticks might merely abut on their ends but it would be necessary in that case to provide means to push the ribbon into the glue setting area. However, the final result would be the same.

My invention is illustrated more or less diagram matically in the accompanying drawings, wherein- Figure l is a flow sheet;

Figure 2 is a .plan view of part of the apparatus for preparing the insulating panels which are intended to be subsequently assembled to build up a tank lining;

Figure 3 is a perspective in part section of a tank with the lining installed.

Like parts are indicated by like characters throughout the specification and claims.

Referring first to the flow sheet, A is the pre-assembly stat on where the individual pieces to be built up are mortised if desired, coated with glue on their opposed surfaces and assembled to form a ribbon. B is the glue setting station where' the ribbon is compressed and the glue by any suitable means set to hold the pieces firmly together in a continuous self-sustaining ribbon. C is the cut ofl station where individual slabs are cut off from the ribbon to desired length. D is the slitting station where each such cut off slabs are horizontally and longitudinally slit into two or more panels of approximate desired thickness. E is the drying station where the slabs are dried with resultant shrinkage. F is the final forming station where the dry panels from the drying station are planed on their opposite faces and on their opposed edges to parallelism and smoothness. G is the trimming station where the ends are out 01f to parallelism and perpendicularity.

Thus panels which are to be used to form the cylindrical side walls of the tank go from the trimming station direct to the tank for assembly. Those panels which are to be used for the floor or top of the tank, however, require further treatment at H the slicing station where each panel is cut diagonally from corner to corner'to make a wedge shaped or pie-shaped piece or slice. 1 is the trimming station Where such pie-shaped pieces are trimmed at both ends to concentricity for assembly in the tank. The panels, either rectangular, direct from 'station G or pie-shaped from station I are immediately conveyed to the tank, gluedand assembled to form a lining made. up of a multiplicity of separate thin panels bent to conform to the cylindrical wall of the tank and .4. cemented in place and to the adjacent panels, as is disclosed in Figure 3.

1 is a work table. It is horizontally disposed and rising upwardly from either side thereof is a guard rail 2. The distance between the guard rails is approximately the width of the ribbon orpanel to be built. A series of wood strips 3, 3 are laid upon the work table. These strips are mortised at their ends at 4 so that all the strips in longitudinal alignment interlock hookwise before they are assembled to form the ribbon shown at the right hand end of Figures 1 and 2. The abutting surfaces of the mortised parts of the strips are coated with glue and the opposite vertical surfaces of the strips are also coated with glue so that all the strips interlocking in alignment are faced with glue wherever one strip meets another. The means for applying the glue and for mortising forms no part of the present invention. Sufiice it to say that the workmen assemble on the work bench these random strips, the vertical thickness of the strips being substantially the same, the horizontal width of all the strips in one line being identical, the vertical width of all the strips being substantially equal to the width between the rails. 5 is a pressure head actuated for example by a hydraulic cylinder 6 adapted to'press all the strips down firmly against the work bench. 7, 7 indicate side pressure plates on both sides of the work table in general alignment with the guard rails 2, Sand 7 measured in a direction parallel to the axis of the Work bench may be approximately six feet long and there is associated with these pressure plates 5 and 7 dielectric heating means shown diagrammatically at 8 so that when there is assembled a ribbon which is fed forwardly into the compression glue setting area associated with the pressures members 5 and 7, light pressure may first be applied by the pressure member 5 holding the strips in place on the work table. Side pressure may then be applied squeezing the strips together and then further pressure may be applied by 5 to compress the strips firmly before, by dielectric heating, the glue is set so that a section for example six feet long and four feet wide and three inches thick-of the assembled ribbon will be set and permanently glued at each operation of the gluing station. 7

While the glue is being set, the Workman will continue to assemble glue coated pieces on the right hand side of the glue setting station in Figures 1 and 2 so that as soon as the glue is set, the next increment of the ribbon may be drawn into the glue setting area.

9 is a vacuum pad which may rest on the glued ribbon slab, or panel as the case may be when it projects beyond the adjacent work station. A cable or other propelling means 10 extend from the pad 9 to any suitable windlass 11.

12 is a guide rail extending across the work table. 13 is a carriage traveling on the guide rail so that the saw 14 supported by the carriage and driven by a motor 15 may be moved across the ribbon to cut otf a panel which, for example, may be twenty feet long.

16 is a band saw traveling around pulleys 17, 18 driven by a motor 19. The band saw on its lower run is parallel with the work table and its teeth face forward toward the direction from which the ribbon has come through the glue setting station. V

As soon as a slab, has been cut oif, vacuum suction is relieved from the vacuum pad 9 and the pad is then carried back to its starting position. The cable 10 moves the pad forwardly, drawing with it the unsevered portion of the ribbon and pushing forward the severed slab against the saw 15 so that the slab is slit in a horizontal plane thus forming two panels, one above the other approximately one and one-half inch thick in a vertical direction, assuming that the ribbon was three inches thick.

These thin flexible panels are then placed in a drying room E where they are dried until the normal moisture 5 content of the wood is reduced and the panel as a result shrinks.

After such shrinkage has reached the desired point, each panel is successively taken out of the drying room and passed through a molder 20 which sizes each panel to exactly the same width and thickness. The ends of the panel 22 are also cut by saws 21 to exact identical length so that we now have a panel, every surface of which is perpendicular to the intersecting surface and their dimension on each panel is the same as similar dimensions on every other panel.

This final shaping takes place after the panels have been dried and reduced in size and it is important that this shaping only takes place at such time because wood will always expand and contract somewhat differently and it is necessary that as the panels are introduced into the tank for assembly, each panel be as near as humanly possible identical in size and shape with every other panel.

Each panel 22 is then immediately conveyed into the tank I for installation as part of the lining, no panel being given its final shaping until the tank is ready to receive it so that the panel shrunk by drying to the desired dimensions may be instantly positioned in the tank as part of the assembly of the built up series of insulating lining layers.

I have used the term glue and gluing in its broadest sense as covering any kind of adhesive material which will permanently hold the pieces of insulating material and the panels together and in place in the tank.

It will be understood that since the individual panels must be bent to conform to the contour of the tank wall, they must be thin enough so that each panel will bend sufficiently without unduly stressing the insulating material. Therefore, they will normally be relatively thin. I have disclosed one method of maintaining such panels which involves slitting a slab which is of greater thickness than the panel because it is convenient to assemble the slab from pieces of Wood or other insulation material of standard commercial thickness. If those pieces were of such a thickness as to give a panel sufficiently thin to be easily bent, there would be no necessity of slitting the slab to make the panel. The slitting is merely, therefore, a convenience in that it enables the assembly of a convenient thickness slab and the manufacture therefrom of a panel of the necessary flexibility. The panel itself will ordinarily not be built up of a plurality of thicknesses. It will be built up of a multiplicity of pieces of uniform thicknesses, the same as the thickness of the panel but glued together side by side. The lining, of course, is itself built up of a multiplicity of thicknesses, a multiplicity of panels one upon the other.

I claim:

1. The method of lining a tank, which consists in gluing together a plurality of pieces of insulating material to form panels of slightly oversize dimensions, drying such panels until the dimensions thereof have been reduced by about 1 to 2%, then while dry, trimming each panel to exact desired length, width and thickness for installation in the tank, then assembling the dry panels side by side and edge to edge and gluing them together in the tank to form a continuous lining therefor, then restoring to said assembled panels a moisture content substantially equal to that of common atmospheric conditions to cause the same to expand and exert a preloading pressure on the lining.

2. The method of manufacturing insulating linings for tanks comprising the steps of assembling and gluing together a multiplicity of pieces of insulating material to form a relatively thick insulating slab of slightly oversize dimensions, slitting the slab to form a plurality of panels whose faces are parallel, then drying such panels until the dimensions thereof have been reduced by about 1 to 2% and thereafter forming and trimming each panel while still dry to the desired size and shape for assembly as a lining in the tank.

3'. The method of manufacturing insulating linings for tanks comprising the steps of assembling and gluing together a multiplicity of pieces of insulating material to form a relatively thick insulating slab of slightly oversize dimensions, slitting the slab to form a plurality of panels whose faces are parallel, then drying such panels until the dimensions thereof have been reduced by about 1 to 2% and thereafter forming and trimming each panel while still dry to the desired size and shape for assembly in the tank, then assembling a plurality of the panels while still dry about the wall of the tank to complete the lining.

4. The method of manufacturing insulating linings for tanks comprising the steps of assembling and gluing together a multiplicity of pieces of insulating material to form a relatively thick insulating slab of slightly oversize dimensions, slitting the slab to form a plurality of panels whose faces are parallel, then drying such panels until the dimensions thereof have been reduced by about 1 to 2% and thereafter forming and trimming each panel while still dry to the desired size and shape for assembly in the tank, then assembling a plurality of the panels while still dry about the Wall of the tank to complete the lining then restoring to said assembled panels a moisture content substantially equal to that of common atmospheric conditions to cause compressive forces to develop in the panels lining the wall of the tank.

5. The method of constructing an insulating lining for tanks which consist in first gluing together a multiplicity of separate pieces of insulating material to form a relatively thin ribbon of substantial length and width, cutting olf from the ribbon a slab of slightly oversize length and width but greater than multiples of the desired thickness, slitting the slab to form a panel of slightly oversize length, width and thickness, drying the panel until the dimensions thereof have been reduced by about 1 to 2%, then while dry trimming the panel to the exact desired length, width and thickness.

6. The method of constructing an insulating lining for tanks which consists in first gluing together a multiplicity of separate pieces of insulating material to form a relatively thin ribbon of substantial length and width, cutting off from the ribbon a slab of slightly oversize length and width but greater than multiples of the desired thickness, slitting the slab to form a panel of slightly oversize length, width and thickness, drying the panel until the dimensions thereof have been reduced by about 1 to 2%, then While dry trimming the panel to the exact desired length, Width and thickness, then gluing a plurality of panels in place in contact with one another and with the wall of the tank to build up a continuous lining for the tank.

7. The method of constructing an insulating lining for tanks which consists in first gluing together a multiplicity of separate pieces of insulating material to form a relatively thin ribbon of substantial length and width, cutting off from the ribbon a slab of slightly oversize length and width but greater than multiples of the desired thickness, slitting the slab to form a panel of slightly oversize length, width and thickness, drying the panel until the dimensions thereof have been reduced by about 1 to 2%, then while dry, trimming the panel to the exact desired length, width and thickness, then gluing a plurality of panels in place in contact with one another and With the Wall of the tank to build up a continuous lining for the tank, then restoring to said assembled panels a moisture content substantially equal to that of common atmospheric conditions to cause compressive forces to develop in the panels lining the wall of the tank.

8. The method of constructing an insulating lining for tanks which consists in first gluing together a multiplicity of separate pieces of insulating material to form a relatively thin ribbon of substantial length and width, cutting off from the ribbon a slab of slightly oversize length and width but greater than multiples of the desired thickness, slitting the slab to form a panel of slightly oversize length, width and thickness, drying the panel until the dimensions asoea q i7 v s thereof have been reduced by about 1 to 2%, then while substantial thickness, greater thanthe thiclgness of the dry, trimming the panel to the exact desired'length, width individual panels is formed. 7 i and' thickness, then gluing a plurality o f panels in place p I incont act with one another and With-the wall'of the tank I e R Citfl i h fi of is patent to build up a continuous lining for the tank, then restoring 5 7 UNITED T T NT to said assembled panels a moisture content substantially I equal to' that of common atmospheric conditions to cause 5; g L "'g y compressive forces to develop in the panels lining the Wall v; 2359937 P 1 1944 of the tank, the lining comprising a plurality of panels 7 c side by side and edge to'edge whereby a lining Wall of 10 

